yes, go with abbrevs, only if the abbrev chosen doesn't frequently occur by itself. (for example, for the word “international”, you don't want “int” as abbrev if you are a programer.)

look up the list of most frequently used english words. They follow some 80/20 rule. That is, 20% has 80% of use. So, basically, you just need to define let's say 20 abbrevs for the top 20 most frequently used words, and you'll save a lot keystroke. (though, there are issues. See below.)

I stopped my experiment. After several tries, it's not worth it. Because

most of these words are already short. 1 to 4 characters.

Any abbrev you add, the abbrev itself add about 1 character. (because it adds a space after expansion. Sometimes you don't want that space. You could make emacs not add space... but basically it's getting complex.)

You start to have issues of chosing which abbrev to use and easy to remember.

Basically you are starting to design a shorthand system. (there are quite a few such systems. Though, none seems to have been designed from today's computer keyboard vantage) The issue now is complexity. You start need to remember your tens of abbrevs.

Now, at this level of efficiency, you probably want to consider something else all together, such as a systematic shorthand system, or voice system, or steno. see Stenotype Machine.

actually, after looking at the steno system, i have a great urge to create a system using the piano keyboard. I think it can replace the steno system for writing English , but most importantly, it'll be much efficient for programing, for emacs, for all general keyboard shortcuts, photoshop shortcuts, Window Manager shortcuts, and replace the computer keyboard. The only problem is, like all such shorthand systems, or reforms of design, notation, or reforms on English, chances are, nobody will use it.